This invention relates to a radio frequency attenuator and more particularly but not by way of limitation to an electrically controlled attenuator for electrically and magnetically controlling transmitted power in a waveguide.
Heretofore, radio frequency signals were attentuated by the use of inserting reflective objects inside the waveguide cavity and adjusting the position and or the amount of the insertion of the reflective objects to achieve a desired attenuation. In practice, this may consist of simply inserting different types of pins into the waveguide and adjusting the insertion depth of the pins with a micrometer. The operator performing the adjustments relies upon the measurement of the reflected or attenuated signal through the waveguide.
This method of attenuating a radio frequency signal is labor intensive and requires difficult work during the test to adjust the reflective pins to a desired depth. Also, vibration or shock may cause the pin to move in its position thereby greatly changing the amount of reflected or attenuated energy. The attenuation is also prone to error caused by small changes in pin position which occur as the pin is locked into position.
Further, modifications to the antenna or randome may necessitiate retuning of the system and the tuning stub or pins may be difficult to find and adjust.
In the following U.S. Patents, U.S. Pat. No. 2,532,157 to Evans, U.S. Pat. No. 2,784,378 to Yager, U.S. Pat. No. 3,798,207 to Reggia, U.S. Pat. No. 2,983,883 to Luhrs, U.S. Pat. No. 2,989,709 to Seidel et al, U.S. Pat. No. 3,063,029 to Hughes, U.S. Pat. No. 3,868,602 to Meddaugh, U.S. Pat. No. 4,092,617 to Titus, U.S. Pat. No. 4,188,594 to Bongianni and an 1949 Article to Miller various types of magnetically controlled microwave attenuators and solenoid controlled apparatus are descried for controlling signals which are both electrically and magnetically controlled. None of these prior art patents specifically describe the unique features and advantages of the subject radio frequency attenuator as described herein.